/* *{
    margin: 0;
    padding: 0;
}
ul,li,ol{
    list-style: none;
}
a{
    text-decoration: none;
    color: #000;
}
img{
    border: 0;
    vertical-align: middle;
}
.clearfix::after{
    content: '';
    display: block;
    clear: both;
}
.fl{
    float: left;
}
.fr{
    float: right;
}
body{
    font-size: 16px;
    font-family: '微软雅黑';
} */
nav, main {
  border: 2px solid #000;
  margin-bottom: 10px;
  padding: 10px;
}

nav > a + a {
  margin-left: 10px;
}

h2 {
  border-bottom: 1px solid #ccc;
  margin: 0 0 20px;
}